结合关联分析和连锁作图定位小麦赤霉病抗性基因

Fusarium head blight (FHB) is a devastating fungal disease of bread and durum wheat worldwide. It commonlly and severely happens in the middle - lower reaches of the Yangtze River, such as Hubei Province, Jiangsu Province and Anhui Province. This disease reduces wheat yield, lowers processing qualities, and makes grain not suitable for human and animal consumption. More recently, FHB has been expanding northwards to the Yellow River - Huaihe River Region. The increasing threat of this disease has created more incentive for plant geneticists and breeders to map the resistances and develop varieties that are resistant to this disease. Application of host resistance is an economically and environmentally friendly control method of FHB. In order to map gene loci underlying FHB resistance, a natural population containing 240 bread wheat varieties/lines and a doubled haploid (DH) population (169 lines) were constructed. The natural population consists of 10 FHB resistant checks, 120 varieties/lines from the Yangtze River Region and 40 varieties/lines from Yellow River - Huaihe River Region, 15 synthetic hexaploid wheat lines, 25 synthetic-derivatives and 30 CIMMYT elite lines. The DH population was produced from a FHB resistant synthetic-derived bread wheat line. These materials were planned to be genotyped by genotyping by sequencing (GBS) and simple-sequence repeat (SSR) markers, and to be phenotyped in artificially inoculated field nurseries in different environments. Genome wide association study and linkage analysis will be conducted using the genotypic and phenotypic data of the two populations. The results of genome wide association mapping will be verified by the result of linkage analysis on the DH population. This project should contribute to understanding the genetic basis and diversity for FHB resistance currently present in synthetic hexaploid wheat and comercial bread wheat varieties.

赤霉病是世界范围内小麦主要病害，我国长江中下游地区是该病常发、重发区域。随着全球性气候变暖、耕作制度以及耕作方式的改变，小麦赤霉病正向黄淮麦区、北方麦区、西南麦区和西北麦区扩展。利用寄主抗性是控制该病主要手段之一。鉴定小麦赤霉病新抗源和抗病基因、丰富小麦赤霉病抗性的遗传多样性，对提高抗赤霉病小麦育种水平十分重要。 本项目将利用Genotyping by sequencing（GBS）标记、微卫星标记（SSR）对一个包含240个品种（系）的自然群体和一个双单倍体（DH）群体（169个DH家系）进行赤霉病抗性的全基因组关联分析和连锁作图，并通过对比关联分析中与抗赤霉病显著关联的GBS标记/单元型和连锁作图定位的抗赤霉病位点分子标记之间的连锁不平衡关系，进一步解析小麦赤霉病的遗传基础，发现新的赤霉病抗源、QTL及其紧密连锁的分子标记，为更好地进行小麦抗赤霉病分子育种提供材料和技术。

小麦赤霉病是一种广泛流行的世界性病害，主要发生在温暖湿润地区。包括湖北省在内的长江中下游冬麦区是我国赤霉病的常发、重发区域。随着全球性气候变暖、耕作制度以及耕作方式的改变，小麦赤霉病正向黄淮麦区、北方麦区、西南麦区和西北麦区扩展。利用寄主抗性是控制该病主要手段之一。鉴定小麦赤霉病新抗源和抗病基因、丰富小麦赤霉病抗性的遗传多样性，对提高抗赤霉病小麦育种水平十分重要。.本项目利用Genotyping by sequencing标记、微卫星标记对一个双单倍体群体（169个家系）进行了赤霉病抗性的连锁作图，对一个包含240个品种（系）的自然群体进行了全基因组关联分析。.将754个Genotyping by sequencing(GBS)和微卫星（SSR）标记位点构建于28连锁群上，总遗传距离达2314.6cM；标记间平均间距为3.1cM。通过复合区间作图，定位到3个赤霉病抗病位点QFhs.cim_1B，QFhs.cim_2D，和QFhs.cim_7A，其中QFhs.cim_2D效应较大，可解释25%的表型变异，其它两个为微效QTL，分别解释4.7%和4.2%的表型变异。QTL定位结果显示3个位点的抗性等位基因均来源于SYN1。含有这3个位点所有抗性等位基因的DH家系，其赤霉病病情指数比含有所有感病等位基因的DH家系低61.4%。.用90K SNP芯片对240份小麦品种（系）进行了分析，结合表型数据，多个环境下共检测到78个显著关联标记，21个显著位点：1A(1)；1B(3)；2D(1)；3B(1)；3D(1)；4A(3)；5A(1)；5B(2)；5D(1)；6A(1)；6B(1)；7A(3)；7B(1)；7D(1)。关联分析检测到的2DL上的抗病位点与双亲群体中定位到的QFhs.cim_2D位置一致。.本项目发现多个抗赤霉病位点，可为抗赤霉病分子标记辅助育种提供材料和方法；建立了微电脑时控弥雾保湿的赤霉病田间接种鉴定方法，获得了国家实用新型专利授权；育成抗赤霉病新品系2个，正在参加各级区域试验；发放抗赤霉病种资100余份次。